General Manager Mike Rizzo, left, introduces Matt Williams as manager in November 2013. Rizzo’s several maneuvers have the Nationals in the hunt for a World Series title, but also capable of competing for years to come. (John McDonnell/The Washington Post)

The Washington Nationals have a six-game division lead, as well as the National League’s best record and margin of victory. They’ve won six in a row, including back-to-back walk-off wins on Saturday and Sunday to sweep the Pittsburgh Pirates. Yet the franchise’s best-known faces, Stephen Strasburg, Bryce Harper and Ryan Zimmerman, are all having disappointing or wasted years. How can those realities both be true?

Maybe one or more of that trio aren’t going to have on-the-Hall-of-Fame-ballot careers that many expected. But, if the Nats can accomplish so much with little from two young household names and a $100 million face-of-the-franchise player, perhaps there’s another message staring at us: Maybe the whole franchise’s future is stronger and more sustainable than suspected.

All fans want a team that might, somehow, win a World Series. But there is another baseball gift to a city, one that keeps giving cumulative pleasure, that competes with titles in its satisfaction. It’s the kind of sustainability that provides winning or contending teams for a decade, or in a few lucky cases, 20 years or more. Such marvels don’t just appear in New York or Los Angeles. Fans in St. Louis, Boston, San Francisco, Atlanta, Oakland, Baltimore and others can tell about it, even if some have to think back a bit.

Could that be happening in D.C.? In a sense, it’s a more controllable dream than talking about crowns which, in baseball, sometimes fall on your head in October as much as you place them there yourself. Data point: Entering Sunday, over the last three years the Nationals have the second-best winning percentage in baseball, behind Oakland and slightly ahead of the Braves, Cards and Dodgers. That D.C., the sport’s unwanted relative for so long, is in such a position may qualify as “delicious irony.”

What’s coming into focus is that the Nats’ organization, from smart drafting and player development through judicious trades and free agent signings, looks better than the Nats’ star power.

Nationals starter Doug Fister allowed two unearned runs in seven innings of work Sunday against the Pirates. (Alex Brandon/AP)

“We don’t have an Andrew McCutchen, Mike Trout or Miguel Cabrera that we can lean on to carry us,” General Manager Mike Rizzo said. “But Ian Desmond, Adam LaRoche and Jayson Werth have carried us for stretches. Harper will carry us. Strasburg will reel off a few wins in a row. We might not have a top-five player in the game but we have 15 to 20 . . . we have 25 good players.”

The Nats only had one all-star this July. But they certainly have a future.

“I think we have reached the point where we have a sustainably good franchise. That’s how we always blueprinted this — to be competitive for the long term. Every move, except trading Zach Walters for Asdrubal Cabrera which was to help us this season, has been with that goal in mind,” Rizzo added. “Your team is built for your core [star] guys. But that’s not enough. We always worry about ‘worst-case scenario’ before anything else.”

In 2012, many things went right and the Nats led the majors in wins. Last year, much went wrong, but the team still won 86 and wasn’t eliminated until the last week. This year they’ve had eight of their best players spend tons of time on the disabled list. “But here we are again,” Werth said.

“The goal when I came here [as a free agent], the ‘sell,’ was that after ’11 the talent on this team was going to be good for a long time,” Werth said. “They’ve kept their word. We’re set up to be extremely competitive this year and next with a window to win [it all]. But the pipeline in the minors now looks like it goes way beyond that.”

All summer, national TV crews have shown up asking, “What’s wrong with Strasburg?” or Harper or Zimmerman or Gio Gonzalez — perhaps the Nats’ best-known names. Or on Sunday when the Nats blow a two-run lead in the ninth, they ask, “What’s wrong with Rafael Soriano?” He’s the closer whose good 2.59 ERA bears no relationship to the fears he instills in Nats fans. That’s legitimate.

Strasburg, despite monster advanced metrics, is 9-10 with a 3.53 ERA. Gonzalez is 6-9 with a 4.06. Zimmerman may miss 100 games with five years and $76 million left on his contract. By different wins above replacement (WAR) methods, Harper is either the Nats’ 18th- or 20th-best contributor, tied with Tyler Moore or Jose Lobaton. Those four, all in their 20s, may go a long time before they have a year when they generate less.

That focus misses the story of an entire team that isn’t a superstar collection. “I get asked about our ‘disappointing season’ in light of ‘expectations,’ ” Rizzo said. “We’re 15 games over [.500] and up by six [games]. Is that disappointing or a testament to everybody who is playing well?”

Sunday’s game highlighted three players who epitomize the Nats’ solid three-legged foundation. Their best pitcher this season took the mound — not Strasburg or Gonzalez, but Doug Fister, acquired from Detroit last offseason in a grand-theft trade. He now has a 12-3 record and a 2.20 ERA after going seven innings without allowing an earned run. The heart of the order was Anthony Rendon and Adam LaRoche. They batted No. 8 and No. 7 on opening day. Now, with Zimmerman and Werth out, they’ve anchored the order and done well.

LaRoche illustrates how seldom the Nats rely on signing free agents; when they have (except for Dan Haren) they’ve generally spent well. Werth was the only mega-contract. Soriano is the only other consequential buy on the roster.

The Nats haven’t stumbled into such players. They analyzed and they knew. They were gleeful, almost giddy, as soon as they drafted Rendon and traded for Fister.

Someday, the Nats hope to see Strasburg or Harper make a run at a Cy Young Award or MVP trophy. They’d like to see Gonzalez win 21 again or Zimmerman put up 110 RBI once more. But what currently defines the Nats is that they haven’t needed those things to have the NL’s best record.

Someday the Nats and their fans may have a top-five-in-the-game superstar. For now, they’ll have to settle for a first-place team that has the second-best record in baseball over the past three years. A weekend full of packed houses at Nationals Park didn’t seem to mind.